Separator for accumulators



40 spaces between Patented Sept. 4, 1934 Y UNITED STATES 1,972,433 SEPARATOR FOR ACCUMULATORS Ernest Thomas Williams and Harry Salmon,

London,

England, assignors to The Expanded Metal Company Limited, London,

England, a

company of Great Britain Application December 22, 1931, Serial No. :82,614 Y In Great Britain December `22, 1930 4 Claims.

This invention relates to insulating separators for use between the plates of an electric accumulator. p

The invention has for its object to provide 5 an insulating separator which 4shall be easy and simple to manufacture, which shall have good insulating properties, which shall offer a low,

obstruction to the circulation of electrolyte, and which shall at the same time be springy and comparatively flexible, whereby effective and efficient separation between the plates of an accumulator may be obtained.

It is of course well known to perforate or slot a plane sheet of insulating material, for example, by stamping holes or slots therein to make an insulating separator for use between the plates of an electric accumulator. Such separators, however, are insufficiently springy and flexible, and, if the perforations or slots are sufficiently large to allow free circulation of electrolyte, the degree of separation obtained often leaves much to be desired.

The present invention obviates these disadvantages and may be regarded as providing an improved insulating separator of the slotted type,

wherein the slots are slits the material on either side of which is bowed or deformed out of the normal initial plane of the unslitted sheet. A separator in accordance with this invention is therefore not planar, in fact, although at a little distance (about arms length) it presents lthe appearance of a fpatterned plane sheet.

According to this invention an insulating separator for use as aninter-plate separator in an accumulator comprises a sheet of insulating material slitted with a plurality of closely'spaced slits in parallel rows, the slits in each row being in line with one another and overlapping the adjacent slits in the next row, the material between saidslits being slightly pushed or deformed out of the' normal plane of the unslitted sheet to form openings for the free circulation of electrolyte, and so as to form a sheet similar in appearance to the material Well known in civil and constructional engineering technique as The amount of deformation is small and consists in pushing the material out of the original plane 50 of the sheet and slightly bowing it.

As is well known, the material known as intermediate expanded metal is the intermediate product obtained in the manufacture of so-called expanded metal by the well known slitting and stretching process, said process consisting in replaced by overlapping- After slitting or, if stretching isgresorted to, after intermediate expanded metal.V

(Cl. 13G-143) passing a sheet between slitting rollers and then stretching it to open out the slits into the characteristic diamond shaped openings of expanded metal. Intermediate expanded meta is the product obtained after slitting but before stretching, the deformation of the material out of the original plane being effected by the slitting rollers in the same operation with slitting.

separators in accordance with this invention may be made by a manufacturing process similar to the slitting" step in the slitting and stretching process of manufacture of expandedv metal above described, and may be of any convenient insulating material, such as chemically treated wood, ebonite, or rubber composition, or cellu- ,m loid. If desired the material obtained from the slitting rolls may be stretched slightly in a direction at right angles to the slits.

In one way of manufacturing an insulating separator, a prepared sheet of rubber composition '5 is employed. This sheet is partially vulcanized so as to be sufllciently stiff to bepassed through a suitable cutting machine, e. g. between slitting rollers and then, if desired, the sheet is expanded or stretched somewhat in a direction at right an- 8o gles to the direction of the parallel rows of slits, the cutting and rolling steps in the process of manufacture being similar to those employed in manufacturing intermediate expanded metal. stretching, the vulcanization process is completed to the degree necessary to constitute a separator of the desired stiffness and other qualities. Alternatively, in place of employing two vulcanzation steps, the rubber may be vulcanized in a single step before slitting and stretching (if any). For example, in the case of an ebonite separator,' the ebonite after heating (e. gipassing through a bath of water at about 85 C.) is simply passed through the slitting rolls. It is found that the resultant product, when allowed to cool, will, during cooling, slightly widen itself in a direction at 4right angles to the directions of the slits,v a sheet, which before slittingwas only 11.5 cms, wide, increasing its width to 13 cms.

Although in many cases insulating separators in accordance with this invention may lbe made by a method of manufacture including steps similar to steps in the well known method of manufacturing expanded metal, i. e. by employing slit- 105 ting rollers (hot) and (if desired) Y divergent y guides for stretching the product obtained from such rollers, it is obvious that the actual method of manufacture employed may be one of any of a Dumber of available methods, the chosen method 1m in any particular cas being determined with regard to the mechanical and other properties of the material employed. Forl example, with certain materials it will be found necessaryV or `de sirable to manufacture an insulating separator in accordance with the present invention by stamping or pressing rather :than by the above described process. The present invention is of gen` eral application to accumulators of all known types. f

The accompanying drawing shows in Figure 1 a.

portion of an insulating separator in elevation in 'accordance with the present invention, Figures 2, 3 and 4 being sections taken on the lines A-B,

C-D and E-F respectively of Figure l.

As will vbe seen, the separator consists of a sheet (of insulatingmaterial) which has been l"sheet of insulating material having a plurality of closely contiguous rows of slits, the slits. of

each individual row being alined with each other and adjacent slits in each row being relatively longand having their extremities close to each other leaving a relatively small extent o! unslitted material between adjacent slits inr the same row, slits in each row being staggered longitudinally relative to slits in the adjacent rows sothat the slits in each row terminate substantially adjacent the mid portions of'sli-ts in the adjacent rows, the material between slits in each row and between adjacent rows of slits being-'disposed out of the general plane of the sheet tdpro#V vide openings having a dimension substantially expanded metal having openings whose dimensions inthe generalplane of the sheet are very small. v l

2'. A battery separator comprising a flexible sheet of insulating material of a structural Iorination similar to intermediate expanded metal, saidsheet differing from intermediate expanded metalin that the material comprising is insulating material instead of metal. i 3. A separator as deiined in claim 1 wherein the sheet is of insulating rubber-containing-material. 4 4. A separator as defined in claim 1 wherein the sheet is of ebonite.

ERNEST THOMAS WILLIAMS. HARRY SALMON.

'normal to the plane 'of the sheet to form a sheet .v resembling inappearance a sheet of intermediate the sheet l 

